| | Duct mastic (RCD) is applied to a joint with a brush. Mastic remains flexible and holds a seal as the duct expands and contracts. |
| | All joints and connections of ducts in non-conditioned space should be sealed with mastic. (Never use standard duct tape; it does not last.) |
| | | Fiberglass mesh tape is embedded in the mastic around the joint for added reinforcement. |
| | Another coating of mastic should be applied over the mesh tape for a long-lasting seal. |
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